The present invention relates to a plate type heat pipe appropriately used to cool electric or electronic parts such as semiconductor chips.
Electric or electronic parts such as semiconductor chips mounted on various equipment such as personal computers or power equipment generate heat in some extent when used. When the electric or electronic parts are excessively heated by the generated heat, the performance thereof is lowered, or the lifetime thereof is shortened. Furthermore, since the size of the electric devices represented by the personal computer or the like becomes smaller, it becomes an urgent task to develop an excellent cooling techniques to cool the small-sized electric or electronic parts mounted on the personal computer or the like.
There is provided an air cooling type cooling method as one of the method of cooling electric or electronic elements which is to be cooled (hereinafter referred to as the xe2x80x9cpart to be cooledxe2x80x9d). More specifically, in the air cooling type cooling method, a fan or the like is installed in the box to accommodate the electric devices on which the parts to be cooled are mounted, and the inside of the box is cooled by the fan or the like so as to prevent the temperature of the parts to be cooled from being excessively risen. The above-mentioned cooling method is particularly effective to cool the relatively large-sized electric devices. However, the above-mentioned cooling method is not appropriate to cool the small-sized electric devices.
In addition to the above-mentioned air cooling type cooling method, there is another widely used cooling method in which a heat sink or fin or the like is connected to the parts to be cooled. In the cooling method, the heat of the parts to be cooled is dissipated through the heat sink. In addition, there is a cooling system in which a heat pipe is installed between the parts to be cooled and the heat sink or fin to improve effectiveness of the heat dissipation. Furthermore, there is developed a technique to attain further improved cooling efficiency in which air is blown to the heat sink, fin or the like by an electrically driven fan.
Heat pipe includes a container having a hermetically sealed hollow portion, i.e., cavity therein. The heat pipe has a function in which a heat is transferred from a heat absorbing portion to a heat dissipating portion, which is apart each other, by means of phase transition and movement of a working liquid accommodated within the hollow portion.
There is a round pipe type heat pipe which is widely used. Recently, a plate type heat pipe comes to attract attention. The plate type heat pipe may be called as a flat type heat pipe, a flat plate type heat pipe or the like. The plate type heat pipe has such a superior feature that the parts to be cooled can be effectively cooled, since the parts to be cooled can be contacted with the container in wide area depending on the shape of the container.
As described above, the plate type heat pipe has the superior feature in which the parts to be cooled is contacted in wide area with the heat absorbing surface of the container. In order to secure the flows of the working liquid from the heat dissipating portion to the heat absorbing portion, i.e., flowing back of the working liquid in the plate type heat pipe having the above-mentioned feature, it is preferable to use the heat pipe in so-called bottom heat mode (namely, the mode in which the heat pipe is used with the heat absorbing portion positioned below the heat dissipating portion).
Accordingly, the heat pipe is preferably installed in such manner that the plate type heat pipe is placed with the heat absorbing surface faced downward, and then, the parts to be cooled is contacted with the heat absorbing surface of thus placed heat pipe, and then, the heat sink is provided on the heat dissipating surface which is positioned upper side of the heat pipe. The above-mentioned installation of the heat pipe in relation to the parts to be cooled is the most ideal installation. According to the above installation, the lower side of the plate type heat pipe becomes the heat absorbing surface, and the upper side of the plate type heat pipe on which the heat sink is provided becomes the heat dissipating surface, thus the plate type heat pipe of the so-called bottom heat mode is obtained.
However, the size of the computer or the like becomes remarkably smaller. Together with the downsizing of the computer or the like, the electric or electronic devices mounting the parts to be cooled is installed not only in a fixed manner (for example, is placed on the desk), but also in a mobile manner (for example, is carried by human being). More specifically, the portable type of electric or electronic apparatus is widely used. In particular, it is considered that the small sized computer is to be used under the condition in which the heat pipe is kept inclined. In view of the above situation, it is expected to be provided the plate type heat pipe excellent in cooling efficiency even in case that the heat absorbing surface is positioned above the heat dissipating surface, i.e., the relative vertical position of the heat absorbing surface tithe heat dissipating surface is reversed (which is called as the so-called xe2x80x9ctop heat modexe2x80x9d).
The object of the present invention is therefore to provide plate type heat pipe excellent in cooling efficiency even in case of the so-called top heat mode, the method of manufacturing same and a cooling apparatus using the plate type heat pipe.
The present invention was made in view of the above-mentioned situation in the process of developing a plate type heat pipe excellent in cooling efficiency even in case of the so-called top heat mode.
The first embodiment of the plate type heat pipe of the present invention comprises:
a plate type container, said container including a heat absorbing side and a heat dissipating side to form a hermetically sealed hollow portion;
at least one heat transfer block, said block being thermally connected to each of inner walls of said heat absorbing side and said heat dissipating side;
a wick, said wick being placed along a side wall of said heat transfer block through said inner wall of said heat dissipating side; and
a working fluid enclosed in said hollow portion.
The second embodiment of the plate type heat pipe of the invention further comprises a securing member to secure said wick and said heat transfer block in close contact.
In the third embodiment of the plate type heat pipe of the invention, said securing member comprises a metal having elasticity.
In the fourth embodiment of the plate type heat pipe of the invention, at least one protruding portion is formed on said heat absorbing side of said container.
In the fifth embodiment of the plate type heat pipe of the invention, said protruding portion is disposed in corresponding to a size and height of a part to be cooled.
In the sixth embodiment of the plate type heat pipe of the invention, at least one of said heat transfer block is joined to said protruding portion.
In the seventh embodiment of the plate type heat pipe of the invention, said heat transfer block and a securing member to secure said wick and said heat transfer block in close contact are placed in at least one of said protruding portion.
In the eighth embodiment of the plate type heat pipe of the invention, said heat transfer block and a securing member to secure said wick and said heat transfer block in close contact are placed in at least one of said protruding portion, and said heat transfer block is placed in at least one of remaining protruding portions and joined thereto.
In the ninth embodiment of the plate type heat pipe of the invention, said wick is secured in close contact between an inner wall of said protruding portion and a side wall of said heat transfer block.
In the tenth embodiment of the plate type heat pipe of the invention, said wick is placed along an inner wall of said heat dissipating side through a side wall of said heat transfer block to extend to an inner wall of said heat absorbing side, a tip portion of said wick being in contact with said inner wall of said heat absorbing side.
In the eleventh embodiment of the plate type heat pipe of the invention, said tip portion of said wick is metal-bonded to said inner wall of said heat absorbing side.
In the twelfth embodiment of the plate type heat pipe of the invention, said protruding portion comprises a protruding portion having different height, and said height of said protruding portion corresponds to a height of a part to be cooled attached to said protruding portion.
The first embodiment of the cooling apparatus comprises the plate type heat pipe as recited in any one of the first to third embodiments arranged to face a printed wiring board on which at least one of parts to be cooled is mounted, and said heat absorbing side is thermally connected to said parts to be cooled.
The second embodiment of the cooling apparatus comprising the plate type heat pipe including said protruding portion as recited in any one of fourth to twelfth embodiments arranged to face a printed wiring board on which parts to be cooled corresponding to said protruding portion in both number and height are mounted, and said protruding portion are thermally connected to said parts to be cooled.
The first embodiment of the method of manufacturing a p late type heat pipe of the invention comprises steps of:
preparing a container including a hollow portion by a plate member as a heat dissipating side and a worked plate member as a heat absorbing side including, at least one protruding portion;
preparing a heat transfer block having a prescribed size and a netlike wick having, a prescribed size;
arranging a securing member and said heat transfer block in at least one protruding portion within said hollow portion of said container;
placing said netlike wick along from a side wall of said heat transfer block through an inner wall of said heat dissipating side;
arranging said netlike wick so as for a tip of said netlike wick to be pinched between said side wall of said heat transfer block and said inner side wall of said protruding portion;
securing, an upper surface and a lower surface of said heat transfer block in close contact to said inner wall of said heat dissipating side and said inner wall of said heat absorbing side, respectively, while said heat transfer block is pushed against said inner side wall of said protruding portion by said securing member to secure said netlike wick and said heat transfer block in close contact;
reducing a pressure within said hollow portion and enclosing a prescribed amount of working fluid.
In the second embodiment of the method of the invention, said heat transfer block is pushed against said inner side wall of said protruding portion by said securing member to secure said netlike wick and said heat transfer block in close contact, and then an upper surface and a lower surface of said heat transfer block is metal-bonded to said inner wall of said heat dissipating side and said inner wall of said heat absorbing side, respectively.
In the third embodiment of the method of the invention, said securing member comprises a metal having elasticity.
In the fourth embodiment of the method of the invention, said protruding portion is, disposed in corresponding to a size and height of part to be cooled.
In the fifth embodiment of the method of the invention, a tip portion of said wick is arranged so as to be in contact with said inner wall of said heat absorbing side.
In the sixth embodiment of the method of the invention, said tip portion of said wick is metal-bonded to said inner wall of said heat absorbing side.